Composition for fingerprinting and method



Patented June 17, 1924.

STATES ALFRED CHARLES OTTO BOOK, OF BROOKLYN, NEW YORK, ASSIGNOR- TO FINGER- ]?RINT MACHINE CORPORATION, A CORPORATION OF NEW YORK.

COMPOSITION FOR FINGERPRINTING AND METHOD.

Ho Drawing.

T 0 all whom it may concern Be it known that I, ALFRED CHARLES O'rro Boon, a citizen of the United States of America, residing at Brooklyn, Kings County, New York, have invented new and useful Improvements in Compositions for Fingerprinting and Methods, of which the following is a specification.

This invention relates to compositions for fixin the impressions of finger prints and the lire upon a paper or other surface whereon a finger or other body has been impressed.

While the compound is especially useful in connection with recording finger prints it may have use in recording other impressions.

It has been found that a highly desirable manner of recording prints is to apply a powder to the impressed surface and afterward ex osing it to heat wherebythe substance o the powder is caused to adhere to or become incorporated with the substance of the impressed object.

I have found that a composition comprising a powder formed by pulverizing the reddish brown or rust colored resin of the dragon tree, which substance is known in commerce as dragons blood is peculiarly adapted to be applied to a print, forms an unusually sharply defined outline, is well adapted to the heat treatment for fixing and, when fixed, is permanent under almost all conditions.

The method employed in using the composition is to make the impression of the finger upon a piece of paper, whereb the natural secretions of the finger or artificial adhesive material, such as oils, applied thereto, form lines upon the paper corresponding to the lines of the finger printed, the dragons blood powder is then applied to the impressed surface, the superfluous powder, that is to say that which does not adhere to the lines, is removed and the paper then bearing the powder adhering to the finger lines only is subjected to sufiicient heat to cause the resin to soften or liquefv and sink into the body of the paper so that on be- Application filed June 1, 1921. Serial No. 474,196.

coming cool it is incorporated with and fixed therein.

The powder employed may be either pure dragons blood or the commercial article which may have a slight amount of impurities mixed with it. Further the color may be modified ,by mixing with the commercial .dragoiis blood an aniline dye of any desired color. A powder of the desired color may be produced by mixing a composition consisting of 99% commercial dragons blood with 1% of aniline dye of the desired color.

An aniline dye is .iot only useful as a coloring matter but also provides means for detecting an attempt to tamper with the impression. The aniline dye is soluble in a large number of substances and almost any substance applied to the impression with the idea of dissolving it would cause the aniline dye to run and discolor the paper so that the attempted tampering would be apparent.

While the invention has been illustrated by a specific composition it may be embodied in other compositions without departin from its spirit and is not, therefore, limited to the precise proportions or ingredients specified. Similarly the method is not limited to the precise details recited but may be varied therefrom without departing from the spirit of the invention.

What I claim is:

1. A powder for fixing prints comprising dragons blood and aniline dye of the color desired.

2. The method of recording a print which consists in making an mpression, applying to the Impression a composition containing drngons blood and subjecting the powdered impression to heat.

3. The method of recording a print which consists in making an impression, applying thereto a powdered composition containing dragons blood and an aniline dye of the color desired and subjecting the powdered impression to heat to fix the same.

In testimony whereof I have signed this specification this 27th day of May 1921.

ALFRED CHARLES OTTO BUCK. 

